The OSI and TCP/IP models, Ethernet framing, MAC addresses, IPv4 and IPv6, ports and protocols, and broadcast vs. collision domains — the on-ramp fluency every later module in this program assumes you already have.
Most networking training jumps straight to configuring devices. This module deliberately starts one level up: how the OSI and TCP/IP models actually map onto a real packet capture, how a switch learns MAC addresses and forwards frames, why IPv4 address scarcity drove both NAT and IPv6 adoption, and what actually identifies "the application" on the wire when a firewall rule references a port number.
By the end of this module you should be able to explain, from first principles, why an oversized flat VLAN degrades performance for every device on it — a question Module 5's switching content and Module 4's addressing content both build on directly.